Inner gear ring with variable tooth-number, the method of varying the tooth-number, and a variable transmission using the inner gear ring

ABSTRACT

A variable transmission comprises a main shift part and a shift mechanism. The main shift part comprises at least an inner gear ring (B) with variable tooth-number which is connected with the shift mechanism. Said inner gear ring (B) is composed of a number of teeth and a pair of tapered discs ( 7,8 ) which are coaxially with said gear ring and the teeth are inter-connected to form a curled rack ( 3 ). The two side surfaces of the inner gear ring (B) are closely contacted with the facing walls of the two tapered discs ( 7,8 ), therefore the inner gear ring (B) is maintained as a circular ring. The end of the rack ( 3 ) is connected to the shift mechanism, and the inner gear ring (B) is engaged with a main planetary gear train disposed coaxially. The transmission ratio of the main planetary gear train varies with the change of the tooth-number of the inner gear ring (B).

BACKGROUND OF THE INVENTION

The present invention relates to a transmission device and itscomponent, and more especially, to an inner gear ring with variabletooth-number, the method of varying the tooth-number, and a variabletransmission for vehicle composed of the inner gear ring with variabletooth-number.

There are two types of transmissions: variable transmissions andcontinuously variable transmissions. Continuously variable transmissionscan keep the motor in optimal working condition all the time so as tomake the overall efficiency higher than the variable transmission. Theexisting continuously variable transmissions CVT, IVT both transferpower depend on friction, so they are inapplicable to high power,heavy-duty vehicles or machines. Moreover, due to the presence ofabrasion, the service life is shorter than that of variabletransmission. In the existing art, the variable transmission generallyincludes no more than 16 shift gears. With more shift gears, thestructure becomes more complicated, and volume, weight and cost arehigher. Furthermore, a clutch is required when shifting, and powerinterruption and loss may take place during shifting, so it ispreferably not to design too many shifts.

BRIEF SUMMARY OF THE INVENTION

The present invention aims at providing an inner gear ring with variabletooth-number and a variable transmission using the inner gear ring withvariable tooth-number which changes the transmission ratio of theplanetary gear train through the tooth-number variation of the innergear ring with variable tooth-number, thus to realize more steps ofspeeds than the existing multi-speed transmission.

The technical solution to realize the present invention is as follows:an inner gear ring with variable tooth-number, characterized in that:comprising a pair of tapered discs disposed coaxially and capable ofchanging axial distance through relative movement, wherein the innerwalls of said two tapered discs are facing each other, a curled rackcomposed of several teeth is set between the two facing walls of thetapered discs, cogs are set on said teeth, the rear section of the rackconsists of narrow teeth, the front section of the rack composed of wideteeth is provided with gear ring connecting interfaces for the access ofthe rear section of the rack, the rear section of the rack passingthrough the connecting interfaces forms a circular inner gear ring, thetwo side surfaces of the inner gear ring are closely contacted with theinner walls of the two tapered discs, the inner walls of the two tapereddiscs are provided with grooves fit for wide teeth, thus to make theinner gear ring formed maintain a circular ring shape, the tooth-numberof the inner gear ring that the rear section of the rack is in or out ofthe inner gear ring through the gear ring connecting interfaces varieswith the change of the relative distance of the two tapered discs.

The method of varying the tooth-number for the inner gearing withvariable tooth-number of the present invention, is characterized inthat, the inner gear ring is engaged with and driven by the outerplanetary gear of the planetary gear train through revolution, the rearsection of the rack is driven to push teeth into or draw teeth out fromthe inner gear ring after the outer planetary gear passes through thegear ring connecting interfaces during rotation, and meanwhile the twotapered discs are driven to make relative movement along the axialdirection to change the adjacent distance, so as to ensure that theinner gear ring is contacted with the inner walls of the tapered discsall the time, and closely contacted between the facing walls of thetapered discs in the form of circular ring shape, the increase ordecrease of tooth-number of the inner gear ring is completed before theouter planetary gear rotates to the gear ring connecting interfaces forthe next time.

With respect to the variable transmission using the inner gear ring withvariable tooth-number of the present invention, its technical solutionis as follows: it comprises a main shift part and a shift mechanism, themain shift part comprises at least an inner gear ring with variabletooth-number which is connected with the shift mechanism, the inner gearring with variable tooth-number is engaged with a main planetary geartrain disposed coaxially, the transmission ratio of the main planetarygear train varies with the change of the tooth-number of the inner gearring.

The abovementioned inner gear ring with variable tooth-number iscomposed of several teeth and a pair of tapered discs disposedcoaxially, wherein cogs are set on said teeth, the teeth connectedmutually constitutes a curled rack, the rear section of the rack isnarrow teeth, the front section is wide teeth on which gear ringconnecting interfaces for the access of the narrow teeth are provided,the rear section of the rack passing through the connecting interfacesforms a circular inner gear ring, the two facing walls of the tapereddiscs are inward concave, the two side surfaces of the inner gear ringare closely contacted between the facing walls of the two tapered discs,and the inner walls of the tapered discs are provided with concave facesfit for the wide teeth, thus to make the inner gear ring form maintain acircular ring shape, the rear section of the rack is connected with theshift mechanism which drives the rear section of the rack to be in orout of the inner gear ring through the gear ring connecting interfacesso as to change the tooth-number of the inner gear ring.

The abovementioned main planetary gear train comprises a main sun gear,an inner planetary gear and an outer planetary gear, wherein the mainsun gear is coaxially disposed between the tapered discs, the innerplanetary gear is engaged with the main sun gear through the bracket ofmain planetary gear carrier, the shafts of the inner, outer planetarygears are articulated via the planetary gear connecting arm and the twogears keep engaged with each other, the outer planetary gear is engagedwith the inner gear ring, the transmission ratio between the mainplanetary gear carrier and the main sun gear varies with the change ofthe tooth-number of the inner gear ring.

The outer planetary gear is directly engaged with the inner gear ringthrough the resistance generated by loads and rotating centrifugalforce, or through a supporting mechanism.

Wherein, the supporting mechanism of the outer planetary gear consistsof a supporting arm, a supporting sliding block and a supporting slidingrail; one end of the supporting arm is connected to the connecting armof the planetary gear, the other end is articulated with the slidingblock, the articulation is coaxial with the outer planetary gear; thesupporting sliding rail and the shaft of the tapered discs are on thesame face and the rail can rotate around the shaft of the tapered discs,the included angle between the supporting sliding rail and the shaft isequal to the semi-tapered angle with the inner walls of the tapereddiscs and moves axially with the tapered disc of the same side; thesliding block slides along the supporting sliding rail, and the outerplanetary gear is engaged with the inner gear ring all the time.

The main sun gear of the variable transmission is connected with thepower input part and the main planetary gear carrier is connected withthe power output part, or vice versa.

A post planetary gear train is configured between the planetary geartrain and power output part; the post planetary gear train is a singlepinion type planetary gear train, and is composed of a sun gear, a gearring and a planetary gear carrier; the main sun gear is connected withthe sun gear, the main planetary gear carrier is linked with the gearring; the main sun gear or main planetary gear carrier is connected withthe power input part, the planetary gear carrier of the post planetarygear train is connected with the power output part.

A traction device is set between the shift mechanism and inner gear ringwith variable tooth-number, wherein the traction device comprises atooth guided grooved rail and a traction rod; the tooth guided groovedrail is arranged along the tangent direction of the inner gear ring andconnected with the first tooth at the front section of the rack, andmakes radial movement with the tooth; the traction rod is arranged onthe plane of the shaft section in the center of the inner gear ring andalong the direction with an arctan (0.5/π) angle with the tooth guidinggrooved rail, and connected with the narrow teeth at the rear section ofthe rack, and moves along this direction under the traction of the shiftmechanism; with the movement of the traction rod along the settingdirection, the rear section of the rack through the gear ring connectinginterfaces by means of drawing out or pushing in teeth is in or out ofthe inner gear ring via the sliding in the tooth guiding grooved rail,and drives the tooth guiding grooved rail to make radial movement alongthe first tooth at the front section of the rack so as to adapt to thechange of the radius of the inner gear ring.

The shift mechanism is synchronous stepping shift mechanism. Itcomprises driver plates; round pins are configured on the driver plates;several grooves fit for the round pins are mounted on the traction rod,and the rotating diameter of the round pins is equal to the distancebetween the adjacent grooves.

The favorable effect of the present invention is that, the inner gearring of the variable tooth-number adopts curled, open type flexible rackfit for the pair of tapered discs, so the change of tooth-number can beeasily realized through pushing, drawing out the rear section of therack, or through the transmission ratio between the self-rotation andrevolution of the outer planetary gear of the planetary gear trainengaged with the rack. While the variable transmission using the innergear ring with variable tooth-number is provided with more steps ofspeeds than the existing multi-speed transmission. With the simplestructure, the number of the steps of speeds can only affect the volume(no impact on the structure) and the shift over 16 steps can be easilyachieved. Therefore, this variable transmission can make the motormaintain nearly the highest efficiency working condition all the time.Moreover, it is engaged type power transmission, so it can be applied inhigh power, heavy duty vehicles or machines, can realize shifting withlow power loss and no power interruption, and the service life is alsolonger than friction type continuously variable transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

The inner gear ring with variable tooth-number, the method of varyingthe tooth-number, and the variable transmission using the inner gearring are explained hereinafter in combination with the drawings and theembodiments:

FIG. 1 shows the curled rack composed of the teeth;

FIG. 2 shows the wide teeth at the front section of the rack and thegear ring connecting interfaces on the rack;

FIG. 3 shows the condition that the inner gear ring is coordinated withone tapered disc;

FIGS. 4 (a) and (b) show the conditions that the distance between thetwo tapered discs are the nearest, the radius of the inner gear ring isthe minimum, the distance between the two tapered discs are thefarthest, and the radius of the inner gear ring is the maximumrespectively;

FIG. 5 is the brief cutaway view of the variable transmission alongaxial direction;

FIG. 6 is the brief view showing the location relations between the mainplanetary gear train and the tooth guiding grooved rail, traction rodwhen the inner gear ring is the maximum;

FIG. 7 is the brief view showing the location relations between the mainplanetary gear train and the tooth guiding grooved rail, traction rodwhen the inner gear ring is the minimum;

FIG. 8 shows the relations between the movements and locations of thetraction rod, shift driver plates and rack.

FIG. 9 is the schematic view showing the coordination of the inner gearring composed of two rack sections and the two main planetary geartrains;

FIG. 10 is the brief cutaway view of Embodiment 2 along axial direction;

FIG. 11 is the brief view showing the location relations of the main sungear, inner planetary gear, outer planetary gear and pinion (P) when theinner gear ring in Embodiment 2 is the maximum;

FIG. 12 is the brief view showing the location relations of the main sungear, inner planetary gear, outer planetary gear and pinion (P) when theinner gear ring in Embodiment 2 is the minimum;

DETAILED DESCRIPTION OF THE INVENTION Embodiment 1

With reference to FIGS. 1˜8, the variable transmission disclosed by thisEmbodiment comprises a main shift part and a post planetary gear train22, the main shift part is connected with the shift mechanism throughthe traction device, wherein the main shift part comprises an inner gearring with variable tooth-number B, a main sun gear 11, an innerplanetary gear 12, an outer planetary gear 13 and a main planetary gearcarrier 14. The post planetary gear train 22 is a single pinion type(Simpson Type) and is composed of a sun gear 23, a gear ring 24 and aplanetary gear carrier 25. The main planetary gear carrier 14 is linkedwith the power input part 20 and the gear ring 24 of the post planetarygear train 22, the main sun gear 11 is connected with the sun gear 23 ofthe post planetary gear train 22, the planetary gear carrier 25 of thepost planetary gear train 22 is linked with the power output part 21.

As shown in FIGS. 1˜4, the inner gear ring with variable tooth-number Bcomprises: a pair of tapered discs 7, 8 disposed coaxially and with twofacing walls, and a curled rack 3 composed of teeth 1 linked mutually.The two tapered discs 7, 8 which (tapered discs 7, 8) are connected byscrews 19 with opposite threads on both ends move along with therotation of the screws 19 so as to change the distance between the twotapered discs 7, 8. Cogs 2 are set on said teeth 1. Both sides of theteeth are the inclined planes fit for the inner walls 9 of the tapereddiscs 7, 8. The rear section 5 of the rack 3 is composed of narrowteeth. The front section 4 of the rack 3 is provided with several wideteeth on which gear ring connecting interfaces A for the access of thenarrow teeth are set, wherein the gear ring connecting interface A onthe first to the fifth wide teeth is in the form of opening “n”, theinterface A on the sixth wide tooth is an enclosed block shape, the rearsection 5 of the rack 3 constitutes the inner gear ring B after passingthrough the gear ring connecting interfaces A; wherein the cogs 2 of thenarrow teeth are set in the middle of the teeth end face, the cogs 2 forseveral wide teeth at the gear ring connecting interfaces A are arrangedon the left and right sides of the teeth end face, with a clearanceequivalent to the width of the cogs 2 of the narrow teeth in the middle,so as to keep the integrity of the cogs at the gear ring connectinginterfaces A for the inner gear ring 3. Concave faces 10 fit for thewide teeth are set in the inner walls 9 of the tapered discs 7, 8, theinner gear ring B is clamped between the inner walls 9 of the tapereddiscs 7, 8 and the concave faces 10 so as to maintain the circular ringshape.

As shown in FIGS. 5˜7, the main sun gear 11 is coaxially set between thetwo tapered discs 7, 8, the inner planetary gear 12 is engaged with themain sun gear 11 through the planetary gear carrier bracket 14; theconnecting arm 15 of the planetary gear is articulated with the shaftsof the outer, inner planetary gears 12, 13 respectively so as to keepthe engagement of the inner, outer planetary gears 12, 13; thesupporting mechanism of the outer planetary gear D is applied to keepthe engagement of the outer planetary gear 13 with the inner gear ringB. When the outer planetary gear 13 passes through the gear ring sectioncomposed of narrow teeth, the cogs in the middle of the end face areengaged with the outer planetary gear 13; when the outer planetary gear13 passes through the gear ring section composed of wide teeth at thegear ring connecting interfaces A, the cogs on both sides of the toothend faces are engaged with the outer planetary gear 13; when the outerplanetary gear 13 passes through the first wide tooth 6 of the gear ringconnecting interfaces A, the outer planetary gear 13 is engaged with acog in the middle of the narrow teeth and cogs on both sides of the widetooth 6 simultaneously. Therefore, in the whole rotating period, theouter planetary gear 13 keeps engagement with the gear ring B, free fromjump discontinuity.

As shown in FIG. 5, the supporting mechanism D of the outer planetarygear comprises a supporting arm 16, a supporting sliding block 18 and asupporting sliding rail 17; one end of the supporting arm 16 isconnected to the connecting arm 15 of the planetary gear, the other endis articulated with the sliding block 18, the articulation is coaxialwith the outer planetary gear 13; the supporting sliding rail 17 and theshaft of the tapered discs 7, 8 are on the same face and the rail canrotate around the shaft of the tapered discs 7, 8, the included anglebetween the supporting sliding rail and the shaft is equal to thesemi-tapered angle with the inner walls of the tapered discs 7, 8 andmoves axially with the tapered disc 8 of the same side; the slidingblock 18 slides along the supporting sliding rail 17, so as to ensurethat the outer planetary gear 13 is engaged with the inner gear ring Ball the time.

Wherein, the traction device connecting the shift mechanism and innergear ring with variable tooth-number B comprises a tooth guiding groovedrail 26 and a traction rod 27. As shown in FIGS. 6˜8, the tooth guidinggrooved rail 26 is arranged along the tangent direction of the innergear ring B and connected with the first tooth 6 at the front section ofthe rack 3. The rear section 5 of the rack 3 passes through the gearring connecting interfaces A, and slides in the tooth guiding groovedrail 26 so as to be in or out of the gear ring B. The tooth guidinggrooved rail 26 can move radially along with the first tooth 6. Thetraction rod 27 is arranged on the plane of the shaft section in thecenter of the inner gear ring B and along the direction with an arctan(0.5/π) angle of about 9.043 with the tooth guiding grooved rail 26, andmoves along this direction, wherein the traction rod 27 is connectedwith the last tooth at the rear section 5 of the rack 3; with thetraction of the shift mechanism, the traction rod 27 moves along thesetting direction, draws out from or pushes into the rear section 5 ofthe rack 3 to be in or out of the inner gear ring B, and drives thetooth guiding grooved rail 26 to make radial movement along the firsttooth 6 so as to adapt to the change of the radius of the inner gearring B. The screws 19 linking the two tapered discs 7, 8 rotate with themovement of the traction rod 27, thus changing the distance between thetwo tapered discs 7, 8.

Wherein, the shift mechanism is synchronous stepping shift mechanism C.It comprises driver plates 29, 30; round pins 31 are configured on thedriver plates 29, 30; several grooves 28 are mounted on the traction rod27, and the diameter of the round pins 31 rotating around the shiftdriver plates (29, 30) is equal to the distance between the adjacentshift grooves 28, the distance of the grooves 28=(teeth spacing of theinner gear ring B)×[1+1/(2π)²]^(1/2), namely, the movement of tractionrod 27 by a distance of grooves 28 just push or draw out a tooth into orfrom the inner gear ring B. The shift driver plates 29, 30 are driven bythe rotation of the supporting sliding rail 17 around the shaft of themain sun gear 11, and the rotating speed of the shift driver plates 29,30 is a half of that of the supporting sliding rail 17 (=½ of thequantity of outer planetary gears). When the outer planetary gear 13passes through the first tooth 6 of the gear ring connecting interfaceA, the round pins 31 are just at the position aligning with the openingof the grooves 28; two shift driver plates 29, 30 can make axialmovement through a mechanical or electromagnetic device. When the shiftdriver plates 29, 30 are in the original location, the round pins 31 arenot in contact with the traction rod 27. As shown in FIG. 8, therotating directions of the two shift driver plates 29, 30 are opposite.When the driver plate 29 rotates clockwise and the traction rod 27 work,the traction rod 27 moves in top-right direction as shown in FIG. 8;when the driver plate 30 rotates anticlockwise and the traction rod 27work, the traction rod 27 moves in bottom-left direction as shown inFIG. 8. Therefore, when shifting is required, the shift driver plate 29or 30 is pushed to the traction rod 27 through a mechanical orelectromagnetic device, with the rotation of the driver plate 29 or 30,the round pins 31 enter into the grooves 28 to poke the traction rod 27for movement, after the round pins 31 rotates out from the grooves 28,the shift driver plate 29 or 30 returns to the original location, roundpins 31 deviate from the traction rod 27; during the shifting above,after the outer planetary gear 13 passes through the first tooth 6 ofthe gear ring connecting interfaces A, the traction rod 27 is moved topush or draw out teeth into or from the inner gear ring B, and drivesthe screws 19 to rotate to change the distance between the two tapereddiscs 7, 8. Before the outer planetary gear 13 passes through the firsttooth 6 of the gear ring connecting interfaces A for the next time, thefollowing are completed: increase or decrease the tooth-number of theinner gear ring B, and change the relative distance between the twotapered discs 7, 8, keep the inner gear ring B in contact with the innerwalls of the tapered discs 7, 8 and maintain circular ring shape.

As shown in FIGS. 6, 7, the tooth-number of the main sun gear 11 Z₁₁=14,that of both the inner planetary gear 12 and outer planetary gear 13 is14, and the tooth-number Z_(B) of the inner gear ring B is at least 46,69 at most. Suppose the tooth-number of the gear ring for the postplanetary gear train is Z₂₄ and that of the sun gear for the postplanetary gear train is Z₂₃, if:(49−Z ₁₁)/Z ₁₁>(Z ₂₄ /Z ₂₃)>(48−Z ₁₁)/Z ₁₁

When the tooth-number of the inner gear ring is 49˜69, the output andinput rotating directions are opposite, 21 steps of speeds areavailable, which will be used as forward shifts; when the tooth-numberof the inner gear ring B is 46˜48, the output and input rotatingdirections are the same, 3 steps of speeds are available, which will beused as the reverse shift.

If the tooth-number of the gear ring 24 for the post planetary gear 22Z₂₄=40 and that of the sun gear 23 for the post planetary gear 22Z₂₃=16, when the tooth-number of the inner gear ring B is 50˜69, theyare the 1^(st)˜20^(th) forward shifts respectively; when thetooth-number of the inner gear ring B is 48, 47, 46, they are the1^(st)˜3^(rd) reverse shifts respectively; when the tooth-number of theinner gear ring B is 49, it is shift “0”, namely, brake for locking, atthis time, the output speed keeps 0 no matter how much rotating speedyou input. The transmission ratio of various shifts is:Input rotating speed/output rotating speed=Z ₁₁(Z ₁₁−tooth-number ofinner gear ring×Z ₂₃/(Z ₂₃ +Z ₂₄))=14/(14−(49+shift levelnumber)×16/56)=−49/shift level number.

Wherein: forward shift levels are 1, 2, 3 . . . 20; reverse shift levelsare −1, −2 and −3.

The negative value of the transmission ratio shows the oppositedirections of input and output rotation. Therefore, the ratio of thefirst level and the 20^(th) level of forward shift is 20 times. Due tothe multiple shifts, the difference of output rotating speeds betweenadjacent shifts is slim, so the variable transmission can realize directshifting without the coordination of the clutch during medium or highspeed, except the starting stage. Springs are used to buffer shiftingimpact, so as to achieve low-loss shifting without power interruption.

Embodiment 2

As shown in FIGS. 10˜12, the difference between the variabletransmission of this Embodiment and that in Embodiment 1 is the lack ofrear-mounted planetary gear train. The transmission in this Embodimentcomprises an inner gear ring B with variable tooth-number and aplanetary gear train coaxially disposed inside, wherein the planetarygear train is composed of a main sun gear 11, an inner planetary gear 12and an outer planetary gear 13. The main sun gear 11 is coaxiallydisposed between the pair of tapered discs 7, 8, and the inner planetarygear 12 is engaged with the main sun gear 11 through the bracket of themain planetary gear carrier 14; the outer planetary gear 13 is providedwith pinions P coaxially connected; the shafts of the inner, outerplanetary gears 12, 13 are articulated with each other through theconnecting arm 15 of the planetary gear, and the inner planetary gear 12keeps engagement with the pinions P; the outer planetary gear 13 isengaged with the inner gear ring B; the main planetary gear carrier 14is linked with the power input part 20, and the main sun gear 11 isconnected with the power output part 21.

Suppose the tooth-number of the inner gear ring B is Z_(B), that of theouter planetary gear 13 is Z₁₃, that of the main sun gear 11 is Z₁₁ andthat of the pinions P is Z_(P), then:

When Z_(B)/Z₁₃>Z₁₁/Z_(P), the directions of the input and outputrotation are opposite, which are used as the forward shift;

When Z_(B)/Z₁₃<Z₁₁/Z_(P), the directions of the input and outputrotation are the same, which are used as the reverse shift;

When Z_(B)/Z₁₃=Z₁₁/Z_(P), the output rotation keeps 0, which is used asbrake for locking.

If the tooth-number Z_(B) of the inner gear ring B takes 46˜69, that ofthe outer planetary gear 13 Z₁₃=20, that of the main sun gear 11 Z₁₁=30,that of the pinions P Z_(P)=12: when Z_(B) is 51˜69,Z_(B)/Z₁₃>Z₁₁/Z_(P), the directions of the input and output rotation areopposite, 19 steps of speeds are available, which are used as theforward shift; when Z_(B) is 46˜49, Z_(B)/Z₁₃<Z₁₁/Z_(P), the directionsof the input and output rotation are the same, 4 steps of speeds areavailable, which are used as the reverse shift; when Z_(B)=50, it isshift “0”, namely, brake for locking, at this time, the output speedkeeps 0 no matter how much rotating speed you input. The transmissionratio of various shifts is:Input rotating speed/output rotating speed=1/(1−(Z _(P) ×Z _(B))/(Z ₁₁×Z ₁₃))=1/(1−(12×(50+shift level number)/(30×20)=−50/shift level number.

Wherein: forward shift levels are 1, 2, 3 . . . 19; reverse shift levelsare −1, −2, −3 and −4; the negative value of the transmission ratioshows the opposite directions of input and output rotation. The ratio ofthe first level and the 19^(th) level of forward shift is 19 times. Dueto the multiple shifts, the difference of output rotating speeds betweenadjacent shifts is slim, so the variable transmission can realize directshifting without the coordination of the clutch during medium or highspeed, except starting stage as described in Embodiment 1. Torquesprings are used to buffer shifting impact, so as to achieve low-lossshifting without power interruption.

Embodiment 3

As shown in FIG. 9, the difference between the variable transmission ofthis Embodiment and that in Embodiment 1 is that the inner gear ring Bis formed by two sections of rack 3 through the connection of both endsin ring-shaped form, wherein the rear section of the first section ofthe rack leads out from the gear ring connecting interface at the frontend of the second section of the rack, the rear end of the secondsection of the rack leads out from the gear ring connecting interface atthe front end of the first section of the rack, and two pairs of inner,outer planetary gears are equipped to balance the center of gravity foreliminating rotating vibration and to bear higher torque. In all theabovementioned embodiments, an inner gear ring with variabletooth-number is adopted. Such inner gear ring can not only be applied tothe aforesaid variable transmission, but also to other shift ortransmission mechanisms. For instance, through the engagement of theinner gear ring B with the outer planetary gear 13 of the planetary geartrain, and driving by the revolution of the outer planetary gear 13, therack is driven to push or draw out teeth 1 into or from the inner gearring B after the outer planetary gear 13 passes through the gear ringconnecting interfaces A during rotation. Meanwhile the two tapered discs7, 8 are driven to make axial movement to change the adjacent distance,in this way, to keep the inner gear ring contacting the inner walls ofthe two tapered discs 7, 8 all the time, and closely contacting betweenthe facing walls of the two tapered discs 7, 8 in the form of circularring shape, the increase or decrease of tooth-number of the inner gearring B is completed before the outer planetary gear 13 rotates to thegear ring connecting interfaces A for the next time.

What is claimed is:
 1. An inner gear ring with variable tooth-numbercomprising a pair of tapered discs (7, 8) disposed coaxially and capableof changing axial distance through relative movement, wherein inwardconcave walls (9) of said two tapered discs (7, 8) are facing eachother, a curled rack (3) composed of several teeth (1) is set betweenthe two facing walls of the tapered discs (7, 8), cogs (2) are set onsaid teeth (1), a rear section (5) of the rack (3) consists of narrowteeth, a front section (4) of the rack (3) is composed of wide teeth isprovided with gear ring connecting interfaces (A) for the access of therear section (5) of the rack, the rear section (5) of the rack (3)passing through the connecting interfaces (A) forms a circular innergear ring (B), wherein the gear ring connecting interfaces (A) on thefirst one or more wide teeth (6) is in the form of opening “n” with theheight of the “n”-shaped wide teeth increasing from the first wideteeth, wherein the rear section (5) of the rack passes through theinterface (A) at a tangent to the inner gear ring (B); two side surfacesof the inner gear ring (B) are closely contacted with the inward concavewalls (9) of the two tapered discs (7, 8); the inward concave walls (9)of the two tapered discs are provided with concave faces (10) fit forthe wide teeth, thus to make the inner gear ring (B) formed maintain acircular ring shape; the tooth-number of the inner gear ring (B) thatthe rear section (5) of the rack (3) is in or out of the inner gear ring(B) through the gear ring connecting interfaces (A) varies with thechange of the relative distance of the two tapered discs (7, 8); theinner gear ring (B) is engaged with at least one planetary gear (13). 2.The inner gear ring with variable tooth-number as claimed in claim 1,characterized in that the inner gear ring (B) is composed of one or moresections of rack (3) through connection at both ends of the one or moresections of rack in ring-shaped form.
 3. A method of varying thetooth-number for the inner gearing with variable tooth-number as claimedin claim 1, comprising steps of (i) engaging and driving the inner gearring (B) by the planetary gear (13) of a planetary gear train throughrevolution, so that the rear section (5) of the rack (3) is driven topush teeth into or draw teeth out from the inner gear ring (B) after theplanetary gear (13) passes through the gear ring connecting interfaces(A) during revolution, (ii) meanwhile driving the two tapered discs (7,8) to make relative movement along the axial direction to change theadjacent distance, so as to ensure that the inner gear ring is contactedwith the inner walls of the tapered discs all the time, and closelycontacted between the facing walls of the two tapered discs (7, 8) inthe form of circular ring shape, and (iii) completing the increase ordecrease of tooth-number of the inner gear ring (B) before the planetarygear (13) passes through the gear ring connecting interfaces (A) duringthe next revolution.
 4. A variable transmission using the inner gearring with variable tooth-number of claim 1, comprising a main shift partand a shift mechanism, characterized in that the main shift partcomprises at least a main planetary gear train driving the shiftmechanism and containing an inner gear ring (B) with variabletooth-number, wherein the inner gear ring (B) with variable tooth-numberforms the gear ring of the main planetary gear train, a transmissionratio of the main planetary gear train varies with the change of thetooth-number of the inner gear ring (B).
 5. The variable transmission asclaimed In claim 4, characterized in that the main planetary gear traincomprises a main sun gear (11), an inner planetary gear (12) and anouter planetary gear (13); wherein the main sun gear (11) is coaxiallydisposed between the two tapered discs (7, 8), the inner planetary gear(12) is engaged with the main sun gear (11) through a bracket of a mainplanetary gear carrier (14); shafts of the inner and outer planetarygears (12, 13) are articulated via a planetary gear connecting arm (15)and the inner and outer planetary gears (12, 13) keep engaged with eachother, the outer planetary gear (13) is engaged with the inner gear ring(B), the transmission ratio between the main planetary gear carrier (14)and the main sun gear (11) varies with the change of the tooth-number ofthe inner gear ring (B).
 6. The variable transmission as claimed inclaim 5, characterized in that the outer planetary gear (13) is directlyengaged with the inner gear ring (B) through the resistance generated byloath and rotating centrifugal force, or through a supporting mechanism(D).
 7. The variable transmission as claimed in claim 6, characterizedin that the supporting mechanism (D) of the outer planetary gearconsists of a supporting arm (16), a supporting sliding block (17) and asupporting sliding rail (17); one end of the supporting arm (16) isconnected to the planetary gear connecting arm (15), the other end ofthe arm (16) is connected with the sliding block (18), the supportingsliding rail (17) can rotate around the axis of the tapered discs (7,8), an included angle between the supporting sliding rail (17) and theaxis of the tapered discs (7, 8) is equal to or similar to asemi-tapered angle of the inner wall (9) of the tapered disc (7 or 8)and moves axially with the tapered disc (7 or 8) of the same side; thesliding block (18) slides along the supporting sliding rail (17), andthe outer planetary gear (13) is engaged with the inner gear ring (B)all the time.
 8. The variable transmission as claimed in claim 5,characterized in that the main sun gear (11) is connected with a powerinput part (20); the main planetary gear carrier (14) is connected witha power output part (21), or the main sun gear (11) is connected withthe power output part (21); the main planetary gear carrier (14) isconnected with the power input part (20).
 9. The variable transmissionas claimed in claim 8, characterized in that a post planetary gear train(22) is configured between the planetary gear train and power outputpart (21); the post planetary gear train (22) is a single pinion typeplanetary gear train, and is composed of a sun gear (23), a gear ring(24) and a planetary gear carrier (25); the main sun gear (11) isconnected with the sun gear (23), the main planetary gear carrier (14)is linked with the gear ring (24); the main sun gear (11) or mainplanetary gear carrier (14) is connected with the power input part (20),the planetary gear carrier (25) of the post planetary gear train (22) isconnected with the power output part (21).
 10. The variable transmissionas claimed in claim 4, characterized in that the main planetary geartrain comprises a main sun gear (11), an inner planetary gear (12) andan outer planetary gear (13); wherein the main sun gear (11) iscoaxially disposed between the two tapered discs (7, 8); the innerplanetary gear (12) is engaged with the main sun gear (11) through abracket of a main planetary gear carrier (14); pinions (P) are connectedwith the outer planetary gears (13) coaxially; the shafts of the innerand outer planetary gears (12, 13) are articulated via a planetary gearconnecting arm (15) and the inner planetary gear (12) is engaged withthe pinions (P); the outer planetary gear (13) is engaged with the innergear ring (B); the main planetary gear carrier (14) is connected with apower input part (20), and the main sun gear (11) is linked with a poweroutput part (21).
 11. The variable transmission as claimed in any onefrom claims 4 and 5-10, characterized in that a traction device is setbetween the shift mechanism and inner gear ring (B), wherein thetraction device comprises a tooth guiding grooved rail (26) and atraction rod (27); the tooth guiding grooved rail (26) is arranged alongthe tangent direction of the inner gear ring (B) and connected with thefirst tooth (6) at the front section of the rack (3), and makes radialmovement with the tooth (6); the traction rod (27) is arranged on aplane of a shaft section in the center of the inner gear ring (B) andalong the direction with an arctan (0.5/π) angle with the tooth guidinggrooved rail (26), and connected with the narrow teeth at the rearsection (5) of the rack (3), and moves along this direction under thetraction of the shift mechanism; with the traction rod (27) movementalong the setting direction, the rear section (5) of the rack throughthe gear ring connecting interfaces (A) by means of drawing out orpushing in teeth is in or out of the inner gear ring (B) via the slidingin the tooth guiding grooved rail (26), and drives the tooth guidinggrooved rail (26) to make radial movement along the first tooth (6) atthe front section of the rack so as to adapt to the change of the radiusof the inner gear ring (B).
 12. The variable transmission as claimed inclaim 11, characterized in that screw holes are set in the tapered discs(7, 8), the screw holes are connected by screws (19) with oppositethreads on both ends, wherein the screws (19) rotate along with themovement of the traction rod (27), and the relative distance between thetwo tapered discs (7, 8) varies with the rotation of the screws (19).13. The variable transmission as claimed in claim 11, characterized inthat the shift mechanism is a synchronous stepping shift mechanism (C)comprising driver plates (29, 30); round pins (31) are configured on thedriver plates (29, 30); several grooves (28) fit for the round pins (31)are mounted on the traction rod (27), and the diameter of the round pins(31) rotating along with the driver plates (29, 30) is equal to thedistance between the adjacent grooves (28).